The invention relates to an electric vehicle on-board charger input relay protection control device and a method thereof. The device comprises an input relay and a microcontroller DSP module. The input and output ends of the microcontroller DSP module are respectively connected with the output and input ends of a CAN communication module and the output and input ends of a memory module. The output end of the microcontroller DSP module is connected with an input relay control module which is connected with the input relay. As the control strategy and hardware connection are improved, the heat produced by the coil of the input relay is reduced, arcing is avoided at work, the charging reliability is improved, the demand for the input relay is reduced, the cost is reduced, and the popularization of the product is facilitated. Meanwhile, the memory module based on an AT24C16 chip is used to record the charging current and relay off-state data, record of the current value and relay state of an on-board charger at failure is facilitated, and a reliable basis is provided for troubleshooting.